1. Field of the Invention
The invention relates to a stream cryptographic method and apparatus therefor. More particularly, the invention relates to a diffusion mechanism for running stream cryptography bit by bit; other than the prior art with a fixed polynomial and Shift operations, the diffusion mechanism is combined flexibly with a variable series of diffusion functions embedded within a diffusion-medium control.
2. Description of the Related Art
The Applicant's following patent application is related to the invention and is incorporated herein by reference: “A Cryptographic Method of Multilayer Diffusion in Multidimension”, application Ser. No. 12/726,833, filed Mar. 18, 2010; the prior invention described a diffusion function for one position AF(p1, p2, . . . , pn), notated herein as AF(i1, i2, . . . , im)=A⊕Ad1i⊕A2i⊕ . . . ⊕Admi⊕S, the encryption/decryption is completed through a diffusion-cycle T, wherein T=2U+1, U=┌log2u┐, u=max(d1, d2, . . . , dm), based on the dimensional magnitude.
The present invention emphasizes multiple diffusion functions at a series of pre-arranged positions to maximize the diffusion cycle. Other than the prior invention for one position, the notation AF(p1, p2, . . . pk) herein is for a series of pre-arranged positions; further, it may be described more delicately as or precisely by A performs the diffusion functions F(p1, p2, . . . pk).